How obesity increases risk of COVID-19 after exposure to SARS-CoV-2

Obesity not only exacerbates the effects of COVID-19 but also significantly increases susceptibility to infection after exposure to SARS-CoV-2, highlighting the need for increased prevention efforts among at-risk populations.

Study: Obesity and age are risk factors for transmission of SARS-CoV-2 infection among exposed individuals. Image credit: Studio Romantic / Shutterstock.com

Obesity has been shown to worsen morbidity and mortality outcomes among individuals infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). In a recent study published in PNAS Nexus, Obesity also increases the risk of contracting coronavirus disease 2019 (COVID-19) after exposure to SARS-CoV-2, researchers reveal.

Does obesity increase sensitivity?

The COVID-19 pandemic, which was caused by the spread of SARS-CoV-2, has caused millions of deaths and hundreds of millions of hospitalizations worldwide.

Throughout the pandemic, most public health authorities have advised personal protective equipment, hygiene measures and social distancing to limit the transmission of SARS-CoV-2. Despite the widespread distribution of vaccines for COVID-19, the continuous mutation of SARS-CoV-2, combined with the inability to achieve universal vaccination and the variability of the protective effects of available vaccines, have limited their effectiveness.

Early in the pandemic, about 5% of hospitalized COVID-19 patients in New York City were obese. Since then, several studies have reported an increased risk of severe disease and mortality from COVID-19 in obese patients. Despite these observations, it remains unclear how obesity may affect the risk of testing positive for COVID-19 after exposure to an infected person.

About the study

Data were obtained from the electronic medical records (EMR) of the Massachusetts General Brigham (MGB) for the current case-control study. The study included a total of 72,613 people with a history of exposure to SARS-CoV-2 or who had been diagnosed with COVID-19, about 97% of whom were adults, 72% were white, and 59% were women.

The aim of the present study was to examine susceptibility, which was defined as the risk of testing positive for COVID-19 after suspected exposure. The study period was between March 1, 2020, and January 25, 2021, which ensured that vaccine immunity did not affect the results, as less than 1% of the Massachusetts population was vaccinated during this period.

Obesity increases sensitivity

Of the 72,613 suspected exposures, 18,477 people subsequently tested positive for COVID-19, which represented 25% of the study cohort. The rate did not differ between age groups or gender.

Obese individuals made up 33.7% of the study cohort, which corresponds similarly to the national and state obesity statistics of 42.4% and 23%, respectively. The prevalence of obesity in all age groups was comparable, with middle-aged adults between 40 and 64 years of age most commonly affected by obesity with a prevalence of 39%.

Obesity was found to increase the risk of testing positive for COVID-19 by 34% compared to non-obese individuals, thus indicating that obesity carries a higher risk of transmission in this population. The increased risk of productive SARS-CoV-2 infection after exposure was consistent across age groups and sex.

Both hypertension and type 2 diabetes mellitus (T2DM) are comorbidities commonly associated with obesity. Since T2DM has been reported to increase the severity and frequency of infections such as COVID-19, researchers were interested in determining whether these clinical factors might contribute to the increased risk of SARS-CoV-2 positivity in this patient population.

When comparing subjects with and without diabetes mellitus, obesity did not increase the risk of SARS-CoV-2 positivity in subjects with diabetes. An increased risk of SARS-CoV-2 infection was observed after exposure in obese adults with and without a history of hypertension.

conclusions

It is important to identify and limit risk factors for SARS-CoV-2 infection to prevent its rapid transmission and progression. Although extrinsic risk factors such as proximity, poor ventilation and aerosol production can be easily identified and modified, intrinsic risk factors such as obesity are not.

Obesity is not only a risk factor for worsening outcomes, but also increases the risk of infection during exposure. Early detection of such populations will be crucial to contain the spread of this infectious disease.”

Among the obese, the elderly, as well as those with hypertension and diabetes, were not found to be at increased risk of SARS-CoV-2 positivity. This lack of effect may be attributed to the markedly increased risk of infection associated with the comorbidity itself, thus masking the effect of obesity. For example, the risk of testing positive for COVID-19 is 44% higher in both obese and diabetic individuals.

The mechanism of increased risk could be due to inflammation, the ability of adipose tissue to harbor SARS-CoV-2, and dysregulated metabolism in obesity that promotes infection. The increasing prevalence of obesity emphasizes the importance of active preventive measures against the transmission of the virus.